Buffing wheels are known for surfacing finishing various articles. For example, in U.S. Pat. No. 4,241,471 to Elias, a buffing wheel is used to polish the surface of a windshield. Similarly, in U.S. Pat. No. 4,606,152 to Michihara et al., a buffing wheel is used to polish the weft guide path of profiled reed blades.
Generally, buffing involves the smoothing and brightening of a surface by an abrasive compound pressed against a workpiece by means of a soft wheel or belt. The abrasive is usually a fine powder mixed with a wax to form a smooth paste. The paste is applied to the wheel as required. The wheel is made of a pliable material such as soft leather, linen, muslin or felt. Soft wheels prevent overpolishing by adapting to the workpiece surface. While buffing has been used to polish surfaces, it has not been used to provide surface contouring due to the pliable nature of the wheel.
Airfoils are generally produced by forging or investment casting which provide a near net shape article. For example, compressor blade may be forged from titanium or nickel alloys. However, some adjustments may be required to achieve the final surface contour. In particular, the root structure which is contoured to slottingly engage a disk may require the selective contouring of edges to ensure proper engagement of the root with the disk, with another benefit being increased fatigue life. Sharp edges provide stress concentration zones which become the focal point for crack initiation and fatigue failure. Utilizing grinding or milling operations to remove such edges has proven satisfactory due to overly agressive metal removal, frictional heating and the requirement for an additional surface finishing operation.